MC input topology: transformers or active stages? - diyAudio
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Old 17th September 2002, 05:56 PM   #1
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Default Subjective and Objective Together

Edited by dice45: thread was split here; original thread: "Remove plastic covers from capacitors" in the Electronics & Parts board

If it sounds decent and makes my feet tap, hell I don't care about measurements, only nowadays it has to be good to do that.
Steve, you make audio isolation transformer boxes yeah ?.
Can you give some objective and subjective findings and corellations of the benefits of these ?.
This is a polite question so no spam callers thanks.

Eric.
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Old 17th September 2002, 06:46 PM   #2
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Default Re: Subjective and Objective Together

Quote:
Originally posted by mrfeedback
If it sounds decent and makes my feet tap, hell I don't care about measurements, only nowadays it has to be good to do that.
And that's EXACTLY how I look at it.

Quote:
Steve, you make audio isolation transformer boxes yeah ?. Can you give some objective and subjective findings and corellations of the benefits of these ?.
Well objectively it's pretty simple. By breaking the DC ground connection between components, you eliminate ground loop and interchassis currents that subsequently produce noise. They also have a natural low pass filter function that filters out RF which can also come from CDPs/DACs which cable shielding has no effect on.

Subjectively I really can't offer much. As I've said previously, I'm wholly right brained when it comes to listening. I don't take the fly speck, analytical approach that many others do and break things down into tiny little pieces and analyze them separately and then try and reach some conclusion.

I just take it in as a whole and decide intuitively whether I like it or not.

Of course if there's some rather gross anomaly that sticks out like a sore thumb, that can catch my attention. But beyond that I'm afraid I'm at a disadvantage when it comes to relating precisely WHY I might prefer something.

Quote:
This is a polite question so no spam callers thanks.
Not to worry. I'm not a "salesman" in the perjorative sense of the word.

Besides, this being a DIY forum, I'd just as soon suggest that if you had an interest, you just buy the raw transformers from Jensen or Sowter and install them INSIDE the component itself which would be preferable to an external, inline solution.

se
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Old 17th September 2002, 07:00 PM   #3
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Steve,

Thanks for the clarification.
Me,I just can't help getting the feeling that in audio the same thing happens as in the pc world.
Things getting ported from the pro (mainframe) world into the consumer market (PC).
By no means a bad thing as such of course.

BTW,wouldn't it be a good idea then to market such a product as yours with XLR in and outputs,or a combination of those ?

Rgds,
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Old 17th September 2002, 07:04 PM   #4
dice45 is offline dice45  Germany
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Steve,
what you say above i can follow and i am with you as far as Jensen trannies are concerned.

I have a pair of Jensen JT-346 as MC input trannie. Except the right piece of wire, this trannie is the best MC input device i came across so far. It is expensive but does make up for it partially by not needing a power supply (and by providing potential isolation for the case i want to have my input grids at -100V.... ). TME an active MC headamp needs dramatic effort for the power supply, preferable NiCd batteries and all the hassle keeping them properly loaded.
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Old 17th September 2002, 07:31 PM   #5
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Quote:
Originally posted by fdegrove
Steve,

Thanks for the clarification.
Me,I just can't help getting the feeling that in audio the same thing happens as in the pc world.
Things getting ported from the pro (mainframe) world into the consumer market (PC).
By no means a bad thing as such of course.
Certainly.

I came into transformers originally as a musician. I got tired of being zapped by touching other equipment or microphones while also touching the strings on my guitar so I fitted my guitar with a transformer and voila. Zap free.

Quote:
BTW,wouldn't it be a good idea then to market such a product as yours with XLR in and outputs,or a combination of those ?
Sure. And if all goes well, I'll be doing just that. Just that my primary goal was to address users with unbalanced inputs as they are the most inherently problematic in that regard.

You can actually feed the InterFace from a balanced source (seeing as the input is inherently balanced). Just need to use an XLR/RCA cable.

Thanks for the comments.

se
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Old 17th September 2002, 07:42 PM   #6
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Quote:
Originally posted by dice45
Steve,
what you say above i can follow and i am with you as far as Jensen trannies are concerned.
Whew! Great! Finally got on the same page! Let's see if we can keep the positive vibe going.

Quote:
I have a pair of Jensen JT-346 as MC input trannie. Except the right piece of wire, this trannie is the best MC input device i came across so far. It is expensive but does make up for it partially by not needing a power supply (and by providing potential isolation for the case i want to have my input grids at -100V.... ). TME an active MC headamp needs dramatic effort for the power supply, preferable NiCd batteries and all the hassle keeping them properly loaded.
Yeah. In my own experience I really haven't found anything that can quite touch a top notch transformer in certain applications. And they've such an elegant simplicity (basically just two lengths of wire and a chunk of nickel) that works well with some of my underlying philosophies.

A project I have on the drawing board now is a low power (about 5-6 watts) single-ended integrated amplifier that will use transformers for attenuation as well as all of the circuit's voltage gain. The battery powered active devices being used as just simple emitter followers for impedance buffering.

Here's a simplified schematic illustrating the basic concept:

<center>
<img src="http://www.q-audio.com/images/tao.jpg">
</center>

Once I get 'round to settling on some higher efficiency speakers, I'll start on the final development. And if I don't **** off too many people here in the meantime, I'll post it here as a project once it's completed.

se
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Old 17th September 2002, 07:59 PM   #7
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Default BATTERIES

Guys,

Sorry to sidetrack here,what exactly is the problem with the batteries here?

preferable NiCd batteries and all the hassle keeping them properly loaded.

I was thinking of experimenting a little by building an all battery supply for headamp through preamp.(tubes B+ 24VDC)
The heaters would be supplied by a regular transformer fed by AC form the mains.
I thought if I bought a couple of 12V NiCads and the PSU (battery)
from Teres I would be off to a good start ?
The Teres come with a load detection system so they're not on charge when in use.
If any of you would have objections I would be glad to hear about it.

Rgds,
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Old 17th September 2002, 08:37 PM   #8
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Default Re: BATTERIES

Quote:
Originally posted by fdegrove
[B]Guys,

Sorry to sidetrack here,what exactly is the problem with the batteries here?

preferable NiCd batteries and all the hassle keeping them properly loaded.
I think he's referring to the additional care and feeding with regard to recharging the batteries. And of course this is within the context of a moving coil step-up where there's no inherent need for an active circuit in the first place. In other words, he's comparing the difference between a simple passive solution versus an active one.

Quote:
I was thinking of experimenting a little by building an all battery supply for headamp through preamp.(tubes B+ 24VDC)
The heaters would be supplied by a regular transformer fed by AC form the mains.
24 volt B+? Can you get away with that with tubes?

Quote:
I thought if I bought a couple of 12V NiCads and the PSU (battery)
from Teres I would be off to a good start ?
Well I guess if you can get by with a 24 volt B+...

Might want to give the NiMHs a try too. They don't have the memory effects of NiCds.

Quote:

The Teres come with a load detection system so they're not on charge when in use.
If any of you would have objections I would be glad to hear about it.
Don't see anything to object to except perhaps that 24 volt B+ but tubes aren't my specialty so I'm just going by intuition here.

se
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Old 17th September 2002, 08:56 PM   #9
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Thumbs up BATTERIES

Steve,

Thanks for your reply.
If anyone is interested in the preamp minus MC part which I have have described to Marjan in the tubes section:
see:
6922

see:
my first valve amp

Yes the NiMH's are the ones to go for,no need for deep discharge and all that rubbish.
I admit to being a bit biased against MC transformers but I may as well give the Jensens a try.

Thks,
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Old 17th September 2002, 09:09 PM   #10
dice45 is offline dice45  Germany
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Quote:
Might want to give the NiMHs a try too. They don't have the memory effects of NiCds.
Back then when NiMH was unavailable, NiCd had the lowest Z. amde listening comparisons, using my SE FET MC headamp i posted about earlier here. NiCd won hands-down over lead-jelly or lead-fluid batteries; AC-fed PS was worst by far.

Last month i got informed by a model airplane geek that NiCd still is top choice for ultra low Z. Just a pain to maintenance NiCd.

My point was: once you tried batteries, you won't be willing to step back to AC, but the trannie sounds better and does not need any PS and batteries at all.

Frank,
no objection against the Teres thing, provided the charge-monitoring and re-loading circuit meets its expectations and keeps its promises. About which i have no info.

Steve,
the Jensens convinced me that much that i abandoned my dreams of an MC-sensitive all-tube phono preamp. My wishful thinking on tubes being noise-free enough for an Ortofon MC. 0.2mV for 0dB.

And before i always considered the mentioned SE FET headamp as best solution but still deterioating sonics, somehow taking the ease away, although under critical AB-ing no flaw could be spotted. Not so with the Jensens. I am not regretting here i put in another amplifying device, okok wire is still better, but then macrodynamics are spoiled and lame and µdynamics are inexistent on low levels, they drown in the noise carpet then.
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